Weakly compact orthogonality preservers on C*-algebras

2010 ◽  
Vol 270 (3-4) ◽  
pp. 709-723
Author(s):  
Francisco J. Fernández-Polo ◽  
Jorge J. Garcés ◽  
Antonio M. Peralta
Keyword(s):  
Weakly Compact ◽  
C Algebras ◽  
Orthogonality Preservers

scholarly journals Compact actions on C*-algebras

1980 ◽  
Vol 21 (2) ◽  
pp. 143-149
Author(s):  
Charles A. Akemann ◽  
Steve Wright
Keyword(s):  
Banach Algebra ◽  
Compact Operator ◽  
Weakly Compact ◽  
C Algebra ◽  
C Algebras ◽  
Compact Perturbations

In Section 33 of [2], Bonsall and Duncan define an elementtof a Banach algebratoact compactlyonif the mapa→tatis a compact operator on. In this paper, the arguments and technique of [1] are used to study this question for C*-algebras (see also [10]). We determine the elementsbof a C*-algebrafor which the mapsa→ba,a→ab,a→ab+ba,a→babare compact (respectively weakly compact), determine the C*-algebras which are compact in the sense of Definition 9, of [2, p. 177] and give a characterization of the C*-automorphisms ofwhich are weakly compact perturbations of the identity.

ORTHOGONALITY PRESERVERS REVISITED

2009 ◽  
Vol 02 (03) ◽  
pp. 387-405 ◽  
Author(s):  
María Burgos ◽  
Francisco J. Fernández-Polo ◽  
Jorge J. Garcés ◽  
Antonio M. Peralta
Keyword(s):  
Linear Operator ◽  
Natural Product ◽  
Bounded Linear Operator ◽  
Complete Characterization ◽  
Bounded Linear ◽  
C Algebra ◽  
Jordan Homomorphism ◽  
C Algebras ◽  
Orthogonality Preservers

We obtain a complete characterization of all orthogonality preserving operators from a JB *-algebra to a JB *-triple. If T : J → E is a bounded linear operator from a JB *-algebra (respectively, a C *-algebra) to a JB *-triple and h denotes the element T**(1), then T is orthogonality preserving, if and only if, T preserves zero-triple-products, if and only if, there exists a Jordan *-homomorphism [Formula: see text] such that S(x) and h operator commute and T(x) = h•r(h) S(x), for every x ∈ J, where r(h) is the range tripotent of h, [Formula: see text] is the Peirce-2 subspace associated to r(h) and •r(h) is the natural product making [Formula: see text] a JB *-algebra. This characterization culminates the description of all orthogonality preserving operators between C *-algebras and JB *-algebras and generalizes all the previously known results in this line of study.

scholarly journals Compact actions on C*-algebras

1980 ◽  
Vol 21 (1) ◽  
pp. 143-149 ◽  
Author(s):  
Charles A. Akemann ◽  
Steve Wright
Keyword(s):  
Banach Algebra ◽  
Compact Operator ◽  
Weakly Compact ◽  
C Algebra ◽  
C Algebras ◽  
Compact Perturbations

In Section 33 of [2], Bonsall and Duncan define an elementtof a Banach algebratoact compactlyonif the mapa→tatis a compact operator on. In this paper, the arguments and technique of [1] are used to study this question for C*-algebras (see also [10]). We determine the elementsbof a C*-algebrafor which the mapsa→ba,a→ab,a→ab+ba,a→babare compact (respectively weakly compact), determine the C*-algebras which are compact in the sense of Definition 9, of [2, p. 177] and give a characterization of the *-automorphisms ofwhich are weakly compact perturbations of the identity.

scholarly journals Elementary operators on prime C*-algebras II

1988 ◽  
Vol 30 (3) ◽  
pp. 275-284 ◽  
Author(s):  
Martin Mathieu
Keyword(s):  
Hilbert Space ◽  
Banach Algebra ◽  
Regular Representation ◽  
Bounded Operators ◽  
Weakly Compact ◽  
C Algebras ◽  
Left Regular Representation ◽  
Left Regular ◽  
Elementary Operators ◽  
The Right

Compact elementary operators acting on the algebra ℒ(H) of all bounded operators on some Hilbert space H were characterised by Fong and Sourour in [9]. Akemann and Wright investigated compact and weakly compact derivations on C*-algebras [1], and also studied compactness properties of the sum and the product of the right and the left regular representation of an element in a C*-algebra [2]. They used the concept of a compact Banach algebra element due to Vala [17]: an element a in a Banach algebra A is called compact if the mapping x → axa is compact on A. This notion has been further investigated by Ylinen [18, 19, 20], who showed in particular that a is a compact element of the C*-algebra A if x ↦ axa is weakly compact on A [19].

An Introduction to K-Theory for C*-Algebras

2000 ◽  
Author(s):  
M. Rørdam ◽  
F. Larsen ◽  
N. Laustsen
Keyword(s):  
C Algebras ◽  
K Theory
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